Hi Guys,
I am trying to plot the negative capacitance as a function of frequency for the XCP for the schematic shown below as
and for that, I have made this testbench as shown below:
I have connected the dc current source at the drain of the MOSFET to Provide Ibias.
At the Source terminal, I am using Large Inductors (1mH) to pass dc signal .
Then I am using port in the circuit and using sp analysis to Plot Img(Y11 ) in the circuit and comparing Img{Y11}=2*pi*f*C
and from that I am finding the value of C vs frequency.
I am referring to the Paper " Frequency Tuning Range Extension in LC-VCOs Using Negative-Capacitance Circuits" and in that they have mentioned that
and Now from dc operating point I have the value of Cgs , gm and all but when I am put these values to see the theoretical values and simulation values I am not seeing a good match between these two results .
So I want to know what I am doing wrong in this testbench in order to plot Cneg Vs frequency